Automatic reclosing circuit breaker



Dec. 2, 1952 VAN RYAN 2,620,382

AUTOMATIC RECLOSING CIRCUIT BREAKER Filed Feb. 2, 1951 ANTHONY VAN RYANhive-Y Patented Dec. 2, 1952 AUTOMATIC RECLOSING CIRCUIT BREAKER Anthonyvan Ryan, South Milwaukee, Wis., assignor to McGraw Electric Company,Milwaukee, Wis., a corporation of Delaware Application February 2, 1951,Serial No. 209,004

6 Claims.

This invention relates to electrical circuit breakers, and particularlypertains to circuit breakers of the reclosing type.

The dvantages of using reclosing circuit breakers have becomeincreasingly apparent, especially with reference to the powerdistribution field. It is well-known that a greater percentage of linefaults are of a temporary nature requiring only momentary line currentinterruption for the clearing of these faults. 'Io require a re-fusingoperation after each occurrence of a fault of a temporary nature wouldimpose a needless burden on utilities.

Various protective devices have been invented to automatically providecurrent interruption on the occurrence of a line fault. In general,these devices have incorporated integrating devices for actuatingcontact lockout mechanisms after a predetermined number of reclosingoperations where the fault is of an enduring nature. In the past,reclosing circuit breakers were designed to open on occurrence of loadsin excess of predetermined values and reclose a predetermined number oftimes determined by the operations of these integrating mechanisms,permanently opening the main line contacts after a predetermined numberof these reclosing operations. Reclosure of the main line contacts underload conditions, and especially under heavy overload, imposed a severeduty on equipment and particularly the arcing contacts. In addition,reclosure under load subjected the power line and line equipment topossible serious damage.

It is therefore a primary object of this invention to provide areclosing circuit breaker for either D. C. or A. 0. operation whichopens the circuit on occurrence of a load in excess of a predeterminedvalue, closing the contacts of an auxiliary circuit after time delaythereby permitting the flow of a limited amount of current at linepotential to determine whether the condition of overload is still inexistence; and to either reclose the main line contacts or retain themin open position, opening the auxiliary circuit contacts as well,depending upon the magnitude of the load resistance or impedance.

It is a specific object of this invention to provide a reclosing circuitbreaker which automatically determines the existence of a permanent linefault without the necessity of subjecting the protected equipment tocontinued re-application of power current and without the requirement ofintegrating or counting devices, and which is provided with an auxiliaryprobing circuit including a current limiting impedance and normally openauxiliary contacts actuated by operation of normally closed maincontacts which are designed to be opened under either temporary orpermanent line fault conditions, the auxiliary circuit also includinglockout means for opening all contacts under certain fault conditions.

Further objects are to provide a, circuit breaker having the aboveenumerated characteristics in which a delayed action means is providedfor the closure of the main contacts during which period the auxiliarycircuit contacts are closed to test or probe the circuit, the auxiliarycircuit contacts also being retarded toward closure by a time delaymeans to provide time for any arcing conditions to clear.

In the single diagrammed drawing of the novel circuit breaker, referencecharacter I refers to the main movable contact adapted to cooperate withstationary contacts 2, and arranged in one side of the power line 3, 4.The load lines are illustrated by the reference characters 6 and 1.

The movable contact I is normally in electrical engagement with thestationary contacts 2 to complete the electrical power circuit to theload. Power is supplied through a series connected main circuitinterrupting solenoid coil 8 which operates the armature 9 to disengagethe contacts I and 2 on the occurrence of predetermined overloadconditions. The armature 9 is attached to one end of an extension or rod10, the opposite end of the rod being pivotally fastened to a rocker armII. A tension spring l2 may be used to bias the contacts toward closedposition, although it is conceivable that gravitational forces acting onthe combined mass of the contact I and armature 9 may be utilized forthis purpose.

An auxiliary movable contact is indicated by the reference character I5,and is adapted to cooperate with stationary contacts Hi. The normallyopen auxiliary movable contact I5 is positioned to be actuated by theoperation of the main solenoid rmature 9 through the rocker arm H. Atime delay means, freely movable in an upward direction and designatedgenerally at ll, is provided to delay closure of the main contacts I and2 after opening under overload. An auxiliary time delay, also freelymovable upwardly and designated generally at 18, is provided for theauxiliary movable contact l5, retarding closure of the auxiliarycontacts I5 and [6 as will be hereinafter described. Both time delays I!and It! may be conveniently in the form of dashpots as shown, or any ofa number of well-known devices.

A lost-motion, resilient device is provided for the auxiliary contact inany of many wellknown forms, and may be in the form diagrammed, whereinenergy may be stored in a compression spring [9. This potential energyis introduced from the rocker arm H to a pin pivotally attached thereto.A flange 2| on the pin 2!] acts as a stop for the spring 19. Theopposite end of the spring l9 rests on the dashpot plunger 22 of theauxiliary time delay l8. A supporting sleeve 23, attached to the plunger22, receives the pin 20. The sleeve 23 is provided with a slottedportion 24 receiving the cars 25 of pin 20.

An extension or rod 26 is attached to the plunger 22 and supports theauxiliary movable contact [5. Stops 2! and 28 are provided for the rods26 and ID, respectively, for a purpose hereinafter described.

A lockout solenoid winding 30 is in series connection with the auxiliarycircuit designated by the reference character 31. A current limitingresistance, or impedance, 32 is provided for the auxiliary circuit 3|,which may be separate or as an integral part of the solenoid winding 30.

The lockout solenoid winding actuates an armature 33 in a downwarddirection under certain predet rmined conditions to be described. Thearmature 33 may be pivotally attached to an L-shaped cam 34, which alsoacts as a stop for the lockout lever arm 35 normally preventing lockout.A tension spring 36 is preferably provided to bias the cam. towards stopposition, further counterclockwise movement being prevented by a stop31. The spring 36 may also be attached at the opposite end to the leverarm 35 to bias the armtoward clockwise movement. It will be apparentthat resilient means may be individually provided for both the arm 35and cam 3411f so desired.

A lever 38 is preferably provided for manual setting after lockout aswill be described below.

The finger may be inte ral with the lever 38, as shown, or with the arm35 aslong as counterclockwise movement of the manual operating lever 38will cause the lever arm 35 to move in the same direction after thefinger 4-2 is contacted. It will be obvious that a certain degree oflost-motion is desirable to permit the various parts 34, 35, and 38 tooperate without restriction. This may he provided :by slidablypositioning the lever 38 on the free end of the rod 40, as shown.

It is to be noted that in the drawing no attempt has been made toindicate the insulation for the various portions of the mechanism,suitable insulation of course being provided in all cases in accordancewith the usual practice. Further, it is to be noted that no guide meanshas been shown as any suitable type of guide means could be employed forthe several movable members.

The operation of the device is as follows:

Assuming that the parts are in normal operating position as shown in thedrawing, it will be apparent that when a load condition in excess of apredetermined value occurs, the main solenoid coil 8 will be energizedand actuate the magnetic armature 9, causing the normally closed maincontacts I and 2 to be disengaged and the power circuit to the loadbroken. At the same instant, the extension or rod ID will cause therocker arm ii to rotate in a counter-clockwise direction,

which rotational motion will be transmitted to the pin 20.

Reclosure of the main contacts 1 and 2 is retarded by the time delaymeans I! in order that the probing or testing operation may be fullyperformed prior to re-engagement of the line contacts. An additionaltime delay means I8 is provided for the auxiliary contacts 5 and I6,preventing the auxiliary contacts from closing until contacts I and 2have been fully separated for a period of time. Such time delay willpermit all contact arcing to clear and further insure closure of theauxiliary circuit contacts after interruption of :the main circuit.Since the armature 9 operates the rocker arm ll immediately on theoccurrence of an overload, this energy must be stored, enduring untilthe contacts [5 and i6 have been closed. This is accomplished by meansof a spring l9 which is compressed by the counterclockwise movement ofthe rocker arm H as transmitted to the pin 20.

On engagement of the contacts I5 and t6, the auxiliary circuit 3| isconnected with the load through line 6. As shown, the auxiliary circuitcomprises a solenoid winding 30 and a resistance or impedance 32. Itwill be apparent that this impedance may be an integral part of thesolenoid winding (not shown). It will also be apparent that otherlockout operating devices such as bimetallic elementsmay be substitutedfor the auxiliary solenoid winding 30. In an A. C. breaker, this may bein the form of a transformer (not shown) containing a natural impedancein its windings and operating a motor or some other device responsive tocurrent flow in the secondary circuit of such transformer.

Line faults causing an increased current in the lines 3 and 4 willaccordingly reduce the impedance across the load lines 6 and I. If thecombined impedance of the fault and the auxiliary resistance 32 is of avalue permitting an increased current to flow in circuit 3| greater thana predetermined Value, the armature 33 will he pulled downwardly causingthe L-shaped cam 34 to rotate clockwise, thus permitting the'springauxiliary contacts 15 and I6 and holding the main contacts I and 2 inopen position.

If the combined impedance value of the fault and the auxiliaryresistance 32 is of a value in excess of that required to permit acurrent flow of sufficient magnitude to pull the armature 33 downward,thus indicating that the fault has disappeared, the main contacts I and2 will be closed after a time delay obtained through the means 11 andthe circuit will be reenergized, restoring the switch to the positionshown in the drawing.

Necessarily, the combined impedance of the winding 30 and the impedance32 must be of such value that when added to the maximum load impedancevalue for minimum trip current of the main circuit interrupter coil 8,minimum trip current will flow through the lockout coil 33.

In order to restore the device to operating condition after lockout, itmay be reset with the aid of the manual operating lever 38. The lever 38is rotated in a counter -clockwise direction about the pin 33 until thefinger 42 contacts the lever arm 35 causing the lever arm to rotate in acounter-clockwise manner against the tensional p l f th spring 36, Thisspring will cause the L-shaped cam 34 to return to normal positionresting against the stop 31 with the lever arm 35 resting thereon. Thiswill then permit the main movable contact; I to return to normallyclosed position with the aid of the tension spring I2 as shown in thediagram. Since the lookout lever arm 35 has caused the auxiliarycontacts [5 and IE to be moved upwardly, they will remain disengaged innormal fashion after resetting operations are completed.

The expression impedance is intended to be broadly construed to coverany form of electrical resistance, whether in the form of the pureresistance of Direct Current circuits or as impedance comprisingresistance, inductance and capacitance components of Alternating Currentcircuits.

From the foregoing description, it will be apparent that a novelreclosing circuit breaker has been provided that acts as a true circuitprobing device and which will determine the overload condition of theload circuit by means of an auxiliary current limiting circuit duringthe initial opening of the main line contacts and either permit the maincontacts to reclose or retain them in open position depending upon themagnitude of the load impedance.

I claim:

1. In an electrical circuit breaker, main switch means biased towardclosed position and arranged to connect a supply circuit with a loadcircuit, condition responsive means in series connection with said mainswitch means for opening said switch means responsive to current of apredetermined value flowing through said load circuit, an auxiliarycircuit including normally open auxiliary switch means arranged forccnnecting said auxiliary circuit with said load circuit subsequent toopening of said main switch means, and an impedance controlled tripmechanism in series connection with said auxiliary circuit and a lockoutmechanism actuated by said trip mechanism and arranged to lock open saidauxiliary switch means and said main switch means responsive to currentof a predetermined value flowing through said impedance controlled tripmechanism.

2. In an electrical circuit breaker, main switch means biased towardclosed position and arranged to connect a supply circuit with a loadcircuit, condition responsive means including a first magnetic coil inseries connection with said main switch means and an armature foropening said main switch means responsive to current of a predeterminedvalue flowing through said coil, time delay means for delaying theclosing of said main switch means; an auxiliary circuit comprising acurrent limiting impedance, normally open auxiliary switch meansarranged for connecting said auxiliary circuit with said load circuitsubsequent to the opening of said main switch means, auxiliary conditionresponsive means including a second magnetic coil in seriesconnectionwith said auxiliary circuit, an armature and a lockoutmechanism arranged to lock open said auxiliary switch means and saidmain switch means responsive to current flow through said secondmagnetic coil above a predetermined value.

3. In an electrical circuit breaker, main switch means biased towardclosed position and arranged to connect a supply circuit with a loadcircuit, condition responsive means including a magnet coil in seriesconnection with said main switch means and an armature for opening saidmain switch means responsive to current of a pedeter'mined value flowingthrough said coil, main switch time delay means for delaying the closingof said switch means, an auxiliary circuit comprising a current limitingimpedance, normally-open auxiliary switch means, an auxiliary time delaymeans operatively associated with said auxiliary switch means andarranged to delay electrical connection of said auxiliary circuit withsaid load circuit subsequent to the opening of said main switch means,and an auxiliary condition responsive mechanism including a lockoutmechanism arranged to lock open said auxiliary switch means and saidmain switch means responsive to current flow through said auxiliarycircuit above a predetermined value.

4. In an electrical circuit breaker including a main switch means biasedtoward closed position, overload responsive means including a coil inseries connection with said main switch means and an armature foropening the switch means when the current controlled by the circuitbreaker exceeds a predetermined value, time delay means operativelyassociated with said switch means to delay closure of said switch means;an auxiliary circuit comprising a current limiting impedance, auxiliaryswitch means operatively associated with said main switch means, delayedaction means for closing said auxiliary switch means subsequent toopening of said main switch means and prior to reclosure of the mainswitch means, and current responsive means; a lockout mechanism, saidcurrent responsive means cooperating with said lockout mechanism to lockopen said auxiliary switch means and said main switch means responsiveto current flow of a predetermined value in said auxiliary circuit; andmanual operating means operatively associated with said lockoutmechanism to permit resetting of said main switch means to normallyclosed position, said manually operating means arranged for moving saidlock-out mechanism to lock out position independent of load conditions.

5. In an electrical circuit breaker including a main switch means biasedtoward closed position for connecting a power circuit with a loadcircuit, condition responsive means including an operating coil inseries connection with said main switch means, said condition responsivemeans arranged to open the switch means responsive to a predeterminedvalue of the current controlled by the circuit breaker, time delay meansretarding reclosure of said main switch means; an auxiliary circuitcomprising a current limiting impedance, auxiliary condition responsivemeans, and normally open auxiliary switch means arranged for connectingsaid auxiliary circuit with said load circuit, said auxiliary switchmeans mechanically operatively associated with said main switch meansand arranged to be closed at a period of time following the opening ofsaid main switch means, said auxiliary switch means being furtherarranged to be normally opened on closure of said main switch means; alookout mechanism operatively associated with said auxiliary conditionresponsive means and arranged to lock open said auxiliary switch meansand said main switch means responsive to current of a predeterminedvalue flowing through said auxiliary circuit.

6. In an electrical circuit breaker, main switch means biased towardclosure and arranged to con nect a supply circuit with a load circuit,current responsive means in series connection with said main switchmeans for opening said switch means responsive to current of apredetermined value flowing through said load circuit, an auxiliarycircuit including normally open auxiliary switch 2,820,882 7 8 meansarranged for connecting said auxiliary cir- REFERENCES CITED cultwith-said load circuit subsequent to opening Th f u f of d operation ofsaid main switch, and an impedance file i s gi fi erences ale moor m thecontrolled. trip mechanism in series connection with said auxiliarycircuit arranged to lock open 5 UNITED STATES PATENTS saidmain switchmeans and said auxiliary switch Number Name Date means responsive tocurrent flown! a predeter- 1,693,328 Anderson Nov. 27, 1928 mined valuethrough said controlled 1,796,817 Walty Mal-.17, 1931 trip mechanism;2,528,194 V-an Ryan Oct. 31, 1950 A Van Ryan et a1 24,

